1. Field of the Invention
The present invention relates to a method for manufacturing a dispersion and to an ink using a dispersion obtained by the above method.
2. Description of the Related Art
In aqueous dispersion materials containing functional materials, as the functional materials, for example, there have been known agricultural chemicals, such as herbicides and insecticides; medicines, such as anticancer agents, antiallergic agents, and antiphlogistic agents; and color materials, such as inks and toners, which contain colorants. As the colorants contained in inks or toners, pigments have started to be used. Concomitant with the trend toward the use of pigments, in order to obtain superior pigment dispersions containing pigments, a method for dispersing pigment using a microjet reactor has been proposed. For example, in Japanese Patent Laid-Open No. 2002-155221, a method for obtaining a pigment suspension has been disclosed in which a precipitation medium and a solution containing a crude pigment are sprayed from respective nozzles to collide with each other in a housing of a reactor chamber.
In Japanese Patent Laid-Open No. 2002-155221, since the solution containing pigment and the precipitation medium are sprayed from the respective nozzles facing each other for mixing, a liquid is scattered in the housing in the reactor chamber. In this case, it is believed that after the scattered liquid and/or reaction product adhere to and precipitate on the inside wall of the housing, they are separated and peeled away from the wall with time. Accordingly, the separated and peeled liquid and/or reaction product may perform secondary reaction with liquids which are newly sprayed from the nozzles in some cases. Hence, by the method disclosed in Japanese Patent Laid-Open No. 2002-155221, it is not always easy to stably obtain a uniform dispersion for a long period of time.